Lubricating grease containing colloidal asbestos



United States Patent Ofiiice 3,433,743 Patented Mar. 18, 1969 3,433,743LUBRICATING GREASE CONTAINING COLLOIDAL ASBESTOS Arnold J. Morway,Clark, and Albert J. Bodner, Wa-

tchung, N.J., assignors to Esso Research and Engineering Company, acorporation of Delaware No Drawing. Filed Apr. 3, 1967, Ser. No. 627,862US. Cl. 25213 5 Claims Int. Cl. Cm 5/00, 5/16, 5/12 ABSTRACT OF THEDISCLOSURE 5 to 40 wt. percent of colloidal asbestos in the form ofsmall tubular fibers having outer diameters of l to 80.0 millimicronsand particle lengths of 2,000 to 30,000 millimicrons will thicken amajor amount of lubricating oil to form a lubricating grease.Optionally, 0.5 to Wt. percent of carboxylic acid such as C to C fattyacids, dimers or trimers of said fatty acids, can be reacted by mixingand heating with the colloidal asbestos, during the grease makingprocess, which makes the grease water-insoluble.

BACKGROUND OF THE INVENTION Field of the invention Lubricating oil isthickened to form a lubricating grease by colloidal asbestos.Optionally, carboxylic acid can be added to the composition and isbelieved to interact with the asbestos. This invention, therefore,relates to lubricating grease containing colloidal asbestos as athickener, wherein the colloidal asbestos can be the sole thickener forthe grease, or wherein it can be used in conjunction with variouscarboxylic acids.

Description of the prior art The use of natural asbestos as a prioringredient of lubricating compositions is old in the art and a number ofvarious grease formulations are taught in the book Lubricating Grease,by C. I. Boner, 2nd edition, pp. 687 et seq. These prior greasesutilized conventional natural asbestos or asbestos floats, both of whichare relatively long fibered asbestos occurring in fibril bundles orag-glomerates almost impossible to separate or deagglomerate. However,this prior fibered asbestos was always used in conjunction with otherthickening agents such as soaps, since the prior long fibered asbestosfibrils or bundles (agglomerates) are too large and will not form athickened homogeneous stable grease gel by itself, but rather reliesupon other ingredients to form the grease or gel-like structure. Inaddition, these prior asbestos greases were often abrasive due to thelarge asbestos fibers.

SUMMARY OF THE INVENTION The asbestos of the present invention differsfrom the aforesaid prior long fibered conventional asbestos in that thisnew asbestos is colloidal asbestos, i.e. the particles are in a verysmall colloidal size, having a large surface area. This colloidalasbestos can be dispersed in the oil to form a gel by itself, withoutsoap, and without settling out from the oil. This colloidal asbestos ischrysotile having the chemical formulation Mg (OH)8Si O The 5 usual modeof occurrence of chrysotile is a cross-fiber configuration in whichfilaments of chrysotile (i.e. bundles of fibers) are closely packedtogether and set at right angles to the walls of cracks and fissuresthat extend through the host rock of the ore body. However, in 1959 0 anunusual deposit of chrysotile asbestos, with properties and a mode ofoccurrence different from the previously known cross-fiber material, wasdiscovered in central California. The ore of this new deposit, insteadof occur- 15 ring in veins, occurs in randomly-oriented, matte-likeflakes and agglomerates of visible asbestos filaments, which in turn aremade up of many thousands of extremely small tubular fibers. The lengthsof these small fibers vary from a few millimicrons to thousands ofmillimicrons, generally 2,000 to 30,000 millimicrons, while thediameters of the fibers vary much less and are usually in the range of lto 80.0, eg 10 to 40.0 millimicrons. While the diameters of the fiberscannot be reduced, their lengths can be further reduced by milling orhomogenization during grease manufacture. A typical colloidal asbestosthat was used in the working examples of the invention had the followingcharacteristics:

Properties of colloidal asbestos used in the working examples 6.0millimicrons. Length 2,500-25,000 m i l l imicrons.

While the colloidal asbestos can be used per se, as the sole greasethickener, it has been further found that the asbestos grease can beeven further improved by the addition of a high molecular weight 'fattyacid which acts to make the grease water-insoluble. It is believed thatthe asbestos neutralizes the fatty acid either by reacting with thefatty acid to form a magnesium soap and/ or by physical combining to theasbestos. In any event the acid im- 55 parts water insolubility to thegrease.

The lubricating oil used in making the lubricating grease compositionsof the invention may be either a mineral lubricating oil or a syntheticlubricating oil. Synthetic lubricating oils which may be used includeesters 60 of dibasic acids (e.g. di-2-ethylhexyl sebacate), esters ofglycols (e.g. C Oxo acid diester of tetraethylene glycol), complexesters (e.g. the complex ester formed by reacting one mole of sebacicacid with two moles of tetra- 3 ethylene glycol and two moles of2-ethyl-hexanoic acid), halocarbon oils, alkyl silicates, sulfateesters, mercaptals, formals, polyglycol type synthetic oils, etc.

If a fatty acid is used to react with the asbestos, it will generally bea C to C preferably C to C20 monocarboxylic fatty acid of any of thetypes generally used in grease making, e.g. substituted orunsubstituted, such as hydroxy substituted, saturated or unsaturated,either synthetic or naturally occuring, or the acid can .be dimers ortrimers of the C to C unsaturated fatty acids. Examples of suchmonocarboxylic acids include capric, caproic, lauric, coconut oil acids(mixtures of capric, caproic and lauric acids), tallow [fatty acids,oleic, palmitoleic, gadoleic, erucic, stearic, linoleic, 12-hydroxystearic, etc. The 12-hydroxy stearic acid is particularly preferredsince it gives a good grease structure at low temperatures.

The aforementioned dimer and trimer acids are polycarboxylic acidshaving the general formula: R(COOH) wherein n is 2 or 3, and wherein Ris a hydrocarbon radical within the range of 24 to 90 carbon atoms,usually 36 to 54 carbon atoms, and may be either saturated or unsaturated. While some of the higher molecular weight acids will besolid, they can be dispersed in the oil by heating the acid in the oilsufficiently to melt the acid, while stirring. Dimers and trimers oflinoleic acid are commercially readily available. Linoleic dimer acid isformed by reaction of two molecules of linoleic acid in a typicalDiels-Alder reaction. This dimer acid is described in US. Patent2,424,588. Its formation and structure is believed to be as follows:

CH=CH O HilLC-(CHDPOH HC=C HC-(CH h-CH;

Linoleic trimer acid is tricarboxylic acid formed by polymerization ofthree molecules of linoleic acid which are linked together by theirunsaturation.

Further description of these linoleic dimer and trimer acids are givenin the catalog Empol Dimer Acids by Emery Industries, Inc., copyright1963.

The grease compositions of the invention will comprise a major amount oflubricating oil and about 5.0 to 40.0 wt. percent, preferably 8 to 30wt. percent of colloidal asbestos. The composition may also containabout 0.5 to 15, preferably 2 to wt. percent of fatty acid to make thegrease water-insoluble, all of said wt. percent being based on theweight of the total composition. The amount of fatty acid can be such asto be substantially neutralized by the colloidal asbestos, althougheither more or less than a neutralizing amount of acid can be used. Inother words, using less acid in any amount will result in a mixture ofneutralized asbestos and unneutralized asbestos, while an ex cess ofacid will result in some free acid, which free acid will generallyimprove the lubricity of the grease.

.4 Various additives can be added to the finished grease lubricant inamounts of 0.1 to 10.0 wt. percent, based on the weight of the finishedgrease. Among additives that can be added are: corrosion inhibitors suchas sodium nitrite, lanolin, wool grease stearine; antioxidants such asphenyl-wnaphthylamine; load carrying agents such as sulfurized spermoil, lead naphthenate; dyes; etc.

The compositions of the invention can be readily formed by simplystirring the colloidal asbestos into the oil while at room temperatures.In the event that fatty acid is also used, it too can be simply added tothe oil, following which the mixture of oil, asbestos and acid ispreferably heated to temperatures of about 250 to 600 F., preferably 320to 450 F., in order to facilitate the interaction and neutralization ofthe asbestos. The higher temperatures will result in dehydrating thegrease, or the water of reaction from the neutralization can be left into form a. cold set grease. Upon cooling, the other additives can beadded to the composition, following which the grease can be homogenized,e.g. in a Charlotte colloidal mill, or a Manton-Gaulin homogenizer, etc.

The invention will be further understood by reference to the followingpreferred embodiments wherein all parts are by weight.

Description of the preferred embodiments EXAMPLE I 10 parts of theaforesaid colloidal asbestos was mixed with parts of mineral lubricatingoil having a viscosity of 80 SUS at 210 F. in a grease kettle, while atroo m temperature of about 77 F. After thoroughly mixing, the resultantcomposition was then passed through a Charlotte colloidal mill having a.003" opening. The milled product was a homogeneous solid greasestructure.

EXAMPLE II 76 parts of mineral lubricating oil having a viscosity of 55SUS at 210 F. and 3 parts of 12-hydroxy stearic acid were added to anelectrically heated jacketed grease kettle and stirred while warming toa temperature of about 125 F. Then 20 parts of the colloidal asbestoswas added and stirred into the reaction mass. Heating was continued to atemperature of about 420 F. in order to complete the reaction of acidand asbestos and to dehydrate the grease. Upon reaching 420 F., heatingwas discontinued and the grease was rapidly cooled while stirring andpassing cold water through the kettle jacket so that in about 15 minutesthe grease temperature had dropped to about 250 E, where one part ofphenyl-alpha-naphthylarnine was stirred into the grease as anantioxidant. The grease was further cooled to F., and then homogenizedby passage through a Morehouse mill having a .032 inch opening to formthe finished grease product.

EXAMPLE III 92 parts of the grease product of Example II was mixed with6 parts of sulfurized sperm oil having a sulfur content of 12 wt.percent and 2 parts of a lead naphthenate concentrate consisting of 30%of lead naphthenate dispersed in 70 wt. percent of a mineral lubricatingoil. The resulting mixture was then stirred while at a temperature of F.until a smooth homogeneous product was obtained.

EXAMPLE 1V Following the general procedure of Example I, a grease wasprepared using a linoleic trimer acid having three carboxylic acidgroups in place of the 12-hydroxy stearic acid and using diflFerentproportions of materials.

The compositions prepared and their properties are summarized in thefollowing table.

TABLE I Formulation (Parts by Weight) I II III IV Colloidal tubularasbestos l M tons-suo) 10. 20. 0 18. 40 15. 0 lz-hydroxy stearic acid 3.0 2. 76 Linoleic trimer acid 2. 0 Phenyl-a-naphthyla 1. 0 92 l. 0Sulfurized sperm oil (12% S) 6. 00 Lead naphthenate (30%) 2. 00 Minerallubricating oil, 80 SUS at 100 F 90 Mineral lubricating oil, 55 SUS at210 F- 76. 0 69. 92 84. 0 ASTM Free acidity or alkalinity Properties:

gppe t o F (0 0) ropping poin 400 00 00+ 400+ AS'IM Penetration, 77 Fmm/lO:

Unworked 305 272 302 28.! Worked 60 strokes. 310 284 302 290 Worked10,000 strokes 320 298 310 350 Water solubility (boiling water)Lubrication Life, NLGI-ABEC Test at 10,000 r.p.m. and 1 200 Pass PassSlump None None Leakage, grams 3. 0 None Timken Test (lbs. load) 1 0.D.,25 millimicrons; I.D., 6 millimicrons, length, 2,500 to 25,000millimicrons.

2 Neutral;

8 0.54% acid calculated as oleic acid.

4 0.5% acid calculated as oleic acid.

5 Excellent.

Smooth.

1 Unstable.

Insoluble.

1 Pass 35 lbs.

Pass 40 lbs.

As seen by the preceding table, the product of Example I consisting ofthe mineral oil thickened with colloidal asbestos as the thickenerformed an excellent appearing grease having a dropping point of 400 F.Example 11 shows that by adding hydroxy stearic acid, the grease wasconverted into a water insoluble, stable greas'e. Example III shows thatthe grease of the invention is compatible with conventional loadcarrying additives, namely, sulfurized sperm oil and the leadnaphthenate. Example IV shows the use of a high molecular weightlinoleic trimer acid also resulted in an insoluble grease having a longlubrication life and good load carrying ability, even without loadcarrying agents, \as indicated by the Timken Test. On the other hand,without the acid present, the load carrying ability would have been muchlower, i.e. about to 15 pounds in the Timken Test.

What is claimed is:

1. A water-insoluble lubricating grease comprising a major amount of alubricating oil and as a thickener about 5 to 40 Wt. percent ofcolloidal asbestos having particle outer diameters of about 1 to 80millimicrons and 3. A lubricating grease according to claim 1, whereinsaid asbestos has particle outer diameters of 10 to 40.0 millimicrons,and said fatty acid is a trimer of linoleic acid.

4. A lubricating grease comprising a major amount of mineral lubricatingoil, about 8 to 30 wt. percent of colloidal asbestos having particleouter diameters of about 10 to 40.0 millimicrons and particle lengths ofabout 2,000 to 30,000 millimicrons reacted with about 2 to 5 wt. percentof C to C fatty acid.

5. A method of preparing the lubricating grease of claim 1, whichcomprises heating said acid and said asbestos together in lubricatingoil to 250 to 600 F. and cooling.

References Cited UNITED STATES PATENTS 1,133,204 3/1915 Warrell 252132,229,368 1/ 1941 Brunstrum et a1 25221 2,268,234 12/1941 Adams et al.25228 2,714,091 7/1955 Puddington et al. 25213 3,010,896 11/1961 Odellet al. 25213 3,113,105 12/1963 Slay-tor et al. 25228 DANIEL E. WYMAN,Primary Examiner.

I. VAUGHN, Assistant Examiner.

U.S. Cl. X.R. 25228

